Shirring attachment for sewing machines

ABSTRACT

This disclosure relates to a shirring attachment for sewing machines equipped with differential feeding mechanisms, and includes a bracket pivotally carrying an arm which in turn carries a shirring blade, the arm and bracket having cooperative abutment means for locating the arm in operative and inoperative positions thereof, and biasing means for positively though releasably maintaining the abutment means in contacting engagement in both positions of the arm. The shirring blade is pivotally journaled to the arm for rotation of about a horizontal aXis, and cam and cam follower means are provided for automatically pivoting the shirring blade to an inoperative position upon the pivoting movement of the arm to its inoperative position.

United States Patent [72] Inventors Mario A. Cima Buffalo Grove; StephenJ. Stasiak, Woodridge, both of Ill. [21] Appl. No. 830,048 [22] FiledJune 3, 1969 [45] Patented Sept. 28, 1971 [73] Assignee Union SpecialMachine Company Chicago, Ill.

[54] SHIRRING ATTACHMENT FOR SEWING MACHINES 21 Claims, 10 Drawing Figs.

[52] US. Cl 112/134, 248/289, 74/527, 16/190 [51] Int. Cl D05b 35/08[50] Field of Search 112/132, 133,134,135, 208, 143, 152, 153; 74/527;248/289; 16/190, 182

[56] References Cited UNITED STATES PATENTS 1,122,322 12/1914 Smith16/190 Primary Examiner1-l. Hampton Hunter AttorneyDiller, Brown, Ramik& Holt ABSTRACT: This disclosure relates to a shirring attachment forsewing machines equipped with differential feeding mechanisms, andincludes a bracket pivotally carrying an arm which in turn carries ashirring blade, the arm and bracket having cooperative abutment meansfor locating the arm in operative and inoperative positions thereof, andbiasing means for positively though releasably maintaining the abutmentmeans in contacting engagement in both positions of the arm. Theshirring blade is pivotally journaled to the arm for rotation of about ahorizontal aXis, and cam and cam follower means are provided forautomatically pivoting the shirring blade to an inoperative positionupon the pivoting movement of the arm to its inoperative position.

V U INVENTORS 5 STEPHEN J SlfiSlAK ATTORNEYS PATENTED SEP28197| SHEET 2OF 3 ATTORNEYS PATENTED SEP28 12m SHEET 3 OF 3 m K/MW 0 W W AH mm? AW MmH w ATTORNEYS SHIRRING ATTACHMENT FOR SEWING MACHINES Sewing machineshaving a differential feed mechanism are particularly useful to producea shirring or similar effect by advancing one workpiece or member,entering into a finished product, at a faster rate than the normal feedof the work as a whole in the region of stitch formation. In performingcertain types of work it is at times desirable to shirr a portion of thework during a part of a seam forming operation, but not during otherparts of such operation. During certain seaming operations it may beundesirable to shirr or ruffle the material, and the shirring mechanismmust therefore also be capable of movement to an inoperative position toclear the throat plate area.

A shirring attachment which is capable of functioning in the mannerheretofore described is disclosed in U.S. Pat. No, 2,965,056 granted onDec. 20, 1960, to Wallenberg et al. The shirring attachment disclosed inthis patent includes a mounting bracket carrying an arm journaled forpivoting movement about a vertical axis to swing the shirring bladel80between operative and inoperative positions. In addition, theshirring blade is pivotally journaled about a horizontal axis in orderthat in the operative position the shirring blade can be pivoteddownwardly toward the feed dogs if shirring operation is desired orupwardly to temporarily terminate the shirring operation withoutswinging the entire arm to its inoperative position. Though thisconventional shirring attachment has been found satisfactory for mostpurposes, several disadvantages thereof have been overcome by thepresent invention. For example, the shirring blade carrying arm of thepresent shirring attachment is positively though releasably maintainedin both the operative and inoperative positions thereof by means of aspring which continually urges cooperative abutment shoulders of the armand the mounting bracket into contacting engagement. Due to thecooperative abutting surfaces of the arm and the bracket, the shirringblade is positively maintained in its exact position relative to thefeed dogs yet can be readily and rapidly moved to an inoperativeposition where it is again positively maintained until returned by theoperator.

The shirring device further includes a finger carried by the shaft ofthe shirring blade which overlies the presser foot whereby upon upwardmovement of the presser foot the shirring blade is automatically pivotedaway from the feed dogs and the throat plate to provide ready access tothis area by the operator. Upon the downward movement of the presserfoot a return spring automatically biases the shirring blade to itsoperative position in engagement with the feed dogs.

Another advantage of the shirring attachment is the provision ofcooperative cam and cam follower means between the mounting bracket andarm such that upon the swinging movement of the arm to its inoperativeposition the shirring blade is automatically progressively lifted awayfrom the differential feed dogs and/or the work toward its inoperativeposition.

In addition to the foregoing advantages, the shirring attachment isrelatively compact thereby facilitating the mounting of the attachmenton most sewing machines having differential feed mechanisms.

In keeping with the foregoing, it is therefore a primary object of thisinvention to provide a novel shirring attachment possessing theadvantages heretofore noted, the attachment including a mountingbracket, an arm carried by the bracket, means journaling the arm to thebracket for pivoting move ment about a generally vertical axis betweenoperative and inoperative positions thereof, a shirring blade carried bythe arm, and means for positively though releasably maintaining the armin each of the operative and inoperative positions thereof by applyingrelative biasing force between the arm and the bracket to maintaincooperative abutment surfaces thereof in contacting engagement in boththe operative and inoperative positions of the arm.

A further object of this invention is to provide a shirring attachmentof the type heretofore defined wherein the cooperative abutment meansare formed by a locating abutment sur- :a pivot pin thereof.

face of the bracket and a pair of abutment surfaces of the arm definingtherebetween an angle generally equal to the angle setoff between theoperative and inoperative positions of the arm.

Still another object of this invention is to provide a novel shirringattachment of the type heretofore set forth wherein the journaling meansincludes a pivot pin journaled in an elongated slot of the bracket, thearm being carried by the pivot pin, and the biasing force being appliedby a spring continually urging the pivot pin and the arm carried therebytoward one end of the elongated slot and a locating abutment surface ofthe bracket to maintain the cooperative abutment means in contactingthough disengageable relationship in both the operative and inoperativepositions of the arm.

Another object of this invention is to provide a novel shirringattachment which includes a shirring blade carried by a shaft having ahorizontal axis and means responsive to the pivoting of the arm aboutthe first-mentioned journaling means for automatically pivoting theshaft and the shirring blade carried thereby upon pivoting movement ofthe arm to this inoperative position.

A further object of this invention is to provide a novel shirringattachment of the type immediately heretofore described wherein theautomatic movement of the shirring blade is effected by a cam followeradjustably secured to the shaft for varying the throw thereof and a camsurface of the bracket.

With the above and other objects in view that 'will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claimed subjectmatter, and the several views illustrated in the accompanying drawings.

IN THE DRAWINGS:

FIG. 1 is a fragmentary top plan view of a sewing machine equipped withan intermittent differential feed mechanism, and illustrates theshirring attachment of this invention secured thereto with an armcarrying a shirring blade disposed in its operative position.

FIG. 2 is a fragmentary front elevational view of the sewing machine ofFIG. I, and illustrates a torsion spring normally urging the shirringblade to its operative position.

FIG. 3 is an end elevational view of the sewing machine, and illustratesa finger connected to the shirring blade shaft in overlying relationshipto a presser foot of the sewing machine whereby upward movement of thelatter automatically pivots the shirring blade to an inoperativeposition.

Fig. 4 is an enlarged top plan view of the shirring attachmentillustrating the shirring blade in its operative position in overlyingrelationship to the differential feed dogs, and biasing means forpositively though releasably holding the arm in its operative position.

FIG. 5 is a top plan view of the shirring attachment of FIG. 4, andillustrates the arm in an inoperative position removed from that shownin FIG. 4.

FIG. 6 is an enlarged side elevational view of the shirring attachmentas viewed in FIG. 2 but detached from the sewing machine, andillustrates a cam follower adjustably carried by an end of the shaftopposite the shirring blade.

FIG. 7 is an end elevational view of the shirring attachment lookingfrom left-to-right in FIG. 6, and more clearly illustrates the camfollower carried by the shirring blade shaft and a cam surface of themounting bracket.

FIG. 8 is a fragmentary sectional view taken generally along line 88 ofFIG. 6, and illustrates the manner in which a spring normally urges thearm to its operative position through FIG. 9 is a bottom view of theshirring attachment partially in cross section, and illustrates themanner in which a spring normally biases the shirring blade to itsoperative position.

FIG. 10 is a cross-sectional view taken generally along line 10-10 ofFIG. 6, and more clearly illustrates the manner in which the camfollower is adjustably secured to the shirring blade shaft.

Referring particularly to FIGS. 1 through 3 of the drawings, a sewingmachine of the type more fully disclosed in the noted Wallenberg et al.patent is provided with a shirring attachment mounted in a manner to bedescribed more fully hereinafter. Reference may be had to the Wallenberget al. patent for details of the machine 10 which are unnecessary for acomplete understanding of the shirring attachment 15. However, it willbe noted that the machine 10 includes a presser foot 11 (FIG. 3)cooperating with a main feed dog 12 and a differential feed dog 13 (FIG.4) whose teeth are exposed through openings (unnumbered) in a plate 14which is suitably secured to a portion of the sewing machine housing(unnumbered). The shirring attachment is secured to the sewing machine10 in such a manner that in the operative position a shirring blade 16thereof is positioned in front of the presser foot 11, as best shown inFIG. 3, and is yieldingly urged downwardly against the differential feeddog 13 and thereby serves to shirr or ruffle the material as it is fedthereunder to the needle in a manner more fully described andillustrated in the latter-noted patent.

Reference is now made more particularly to FIGS. 4 through 10 of thedrawings, wherein the shirring attachment 15 will be seen to include amounting bracket, generally designated by the reference numeral 17,having a vertical platelike portion 18 provided with elongated openings20, 21 (FIGS. 7 and 8). The surface (unnumbered) of the bracket portion18 shown in FIG. 8 is seated against the housing (unnumbered) of thesewing machine 10 as shown in FIG. I, and fastened thereat by screws 22passing through the openings 20, 21 and secured in threaded bores(unnumbered) of the machine housing. The slots 20, 21 permit theshirring attachment 15 to be adjusted vertically for proper positioningof the shirring blade 16 relative to the feed dog 13.

A horizontal portion 23 of the bracket 17 is provided with an elongatedslot 24 (FIGS. 4, 5 and 8) having opposite arcuate end faces 25, 26 (FIG8). A stub shaft or pivot pin 27 is positioned in the slot 24, as bestshown in FIG. 8, with an enlarged head 28 thereof resting atop an uppersurface 30 of the horizontal portion 23. A threaded end portion(unnumbered) of the pin 27 passes through an opening 31 of an arm 32which is secured to the pivot pin 27 by a nut 33. The axis of the pin 27is generally vertical and the arm 32 is therefore free to pivot or swingabout the axis of the pin 27 in a horizontal plane between the operativeposition shown in FIG. 4 and the inoperative position of FIG. 5. Inaddition, because of the elongated nature of the slot 24, the arm 32 maybe shifted to the left as viewed in FIG. 8 against the biasing force ofa spring 34 housed in a bore 35 of the horizontal portion 23 and bearingagainst the pivot pin 27. The tension of the spring 34 can be adjustedby means of a set screw 36 received in a threaded counterbore 37 whichalso includes a locking screw 38. The purpose of the spring 34 is tomaintain cooperative abutment means 40, 41 (FIG. 9) of the bracket 17and the arm 32 in contacting engagement in the operative position of thearm 32 and abutment means 40, 42 in contact in the inoperative positionofthe arm 32 (FIG. 5). As best shown in FIG. 9, the abutment means 41,42 of the arm 32 are merely end faces of the arm which are disposed atan angle of 90 relative to each other and which merge with each other bya radius 43. The abutment means 40 of the bracket 17 is merely ashoulder which will flushingly engage the end faces 41, 42 in therespective operative and inoperative positions illustrated in FIGS. 4and 5.

Referring particularly to FIG. 4, when it is desired to move the arm 32from the operative position illustrated therein, the same is swung inthe direction of the unnumbered headed arrow which progressively pivotsthe arm 32 about the axis of the pivot pin 27. During this movement theradius 43 bears against the surface 40 and progressively shifts thepivot pin 27 away from the end face 25 of the slot 24 during which timethe spring 34 is progressively collapsed. After the arm 32 has beenswung approximately 45 from that illustrated in FIG. 4, the shoulder 43passes to the left of the axis of the pivot pin 27, as viewed in FIG. 4,and the force of the spring 34 returns the pin 27 toward the end face 25with a snaplike motion bringing the surface 42 of arm 32 into contactwith the shoulder 40, as shown in FIG. 5. When it is desired to returnthe arm 32 from the inoperative position shown in FIG. 5 to theoperative position of FIG. 4, the arm 32 is swung clockwise as viewed inFIG. 5 whereupon the shoulder 43 again bears against the surfaceshifting the pivot pin 27 downwardly, as viewed in FIG. 5, until such atime as the arm 32 has been pivoted approximately after which thecompressed spring 34 will return the arm 32 with a snapping action tothe operative position of FIG. 4. From the foregoing it will be notedthat the cooperative abutment means 40-42 in cooperation with the springbiased shiftable mounting of the pivot pin 27 functions to maintain thearm 32 positively though releasably positioned in both the operative andinoperative conditions of the arm 32.

The arm 32 includes a threaded bore 45 (FIGS. 4 and 5) in which isthreadably received an adjusting screw 46 having an exposed end 47 and alocking screw 48. In the operative position (FIG. 4) of the arm 32 theexposed end 47 of the adjusting screw 46 contacts a face 50 of themounting bracket 17. As is best visualized in FIG. 4, the screw 46 canbe adjusted inwardly or outwardly of the threaded bore 45 to accuratelyadjust the position of the shirring blade 16 in its operative positionby limiting the pivoting movement of the arm 32 to a point at which theface of the screw 46 contacts the surface 50.

The underside of the arm 32 includes a housing 51 in which is rotatablyjournaled a shaft 52 having oppositely exposed ends 53, 54. The end 53of the shaft 52 has the shirring blade 16 attached thereto by means of aslot 55 and fasteners 56 (FIGS. 5 and 7). A midportion of the shaft 52is received in a bore 57 (FIG. 9) of the housing 51 and carries a pairof collars 60, 61 having respective reduced end portions 62, 63 receivedin the bore 57. A torsion spring 65 surrounds the shaft 52 and the ends(unnumbered) thereof are received in openings 66, 67 of the respectivecollars 60, 61. The collar 61 preferably has a plurality of notches 68(FIG. 10) for receiving a wrenchlike tool for rotating the collar 61 toincrease or decrease the tension of the spring 65. A set screw 70secures the collar 61 in any desired adjusted position thereof, and in alike manner the collar 60 can be secured in any desired position ofrotation relative to the shaft 52 by means of a set screw 71. The spring65 serves to urge the shaft 52 in a counterclockwise direction as viewedin FIGS. 3 and 7 to hold the rearward free end of the shirring blade 16in cooperative relationship to the feed dog 13.

The collar 60 additionally includes a lifting finger 72 having an endportion 73 partially overlying the shirring blade 16 and in theoperative position of the arm 32 (FIGS. 1, 3 and 4) the end 73 of thelifting finger 72 overlies the presser foot 11, as is best illustratedin FIG. 3. Therefore, upon the upward movement of the presser foot 11 ina conventional manner, the lifting finger 72 is rotated clockwise, asviewed in FIG. 3, to thereby automatically rotate the shaft 52 throughthe collar 60 and raise the shirring blade 16 away from the feed dog 13.Since the collar 60 can be set in any particular position of rotationrelative to the shaft 52 by the set screw 71, the degree which theshirring blade 16 is lifted can be adjusted by positioning the end 73 ofthe lifting finger 72 at any desired position above the presser foot 11.It should, however, be noted that upon changing the position of thecollar 60 an increase or a decrease in the tension of the spring 65 willtake place, and this may have to be compensated for by the rotation ofthe collar 61 in the manner heretofore described. However, thisconstruction also permits the tension of the spring 65 to be varied byadjusting the collar 60 relative to the shaft 52.

The shirring attachment is also provided with means responsive to themovement of the arm 32 from the operative position (FIG. 4) to theinoperative position (FIG. 5) to automatically progressively rotate theshaft 52 and thus lift the shirring plate 16. This function is providedby a cam follower 75 (FIGS. 7 and 9) forming an extension of a collar 76which is adjustably secured in any desired position to the exposed end54 of the shaft 52. The cam follower 75 is in alignment with a camsurface 78 formed in the undersurface (unnumbered) of the horizontalportion 23. Referring particularly to FIGS. 7 and 9 in which the arm 32is illustrated in the operative position with the shirring blade l6adjacent the feed dog 13, clockwise pivoting of the arm 32, as viewed inFIG. 9, progressively causes the cam follower 75 to be guided along thecam surface 78 resulting in a clockwise rotation of the shaft 52, asviewed in FIG. 7, and thus an upward lifting of the rearward end of theshirring blade 16. Likewise, upon pivoting movement of the arm 32 fromthe inoperative position shown in FIG. 5 to the operative position shownin FIG. 4 the spring 65 will progressively return the shirring blade 16to its operative position (FIG. 7) as the cam follower 75 progressivelymoves along the cam surface 78. In this manner any movement of the arm32 is accompanied by an automatic lifting or lowering of the shirringblade 16.

The cam follower 75 may also be provided with an opening 80 (H65. 7 andthrough which may be attached a link of a foot-treadle operated chainfor pivoting the shirring blades 16 at times other than those heretoforedescribed.

While preferred forms and arrangements of parts have been shown inillustrating the invention, it is to be clearly understood that variouschanges in details and arrangement of parts may be made withoutdeparting from the spirit and scope of this disclosure.

We claim:

1. A shirring attachment for a differential feed sewing machinecomprising a mounting bracket, a pivot pin, means mounting said pivotpin for transverse shifting movement relative to said bracket and to thepivot pin axis, an arm received on said pivot pin for pivotal movementabout the axis thereof between operative and inoperative positions, arotary shaft journaled on said arm, a shirring blade carried by saidrotary shaft, spring means engaging said rotary shaft for biasing'saidshaft in a predetermined angular direction, means limiting said angulardistance between said operative and said inoperative positions to 90,and means for positively through reasonably maintaining said arm in eachof said operative and inoperative positions.

2. The shirring attachment as defined in claim 1 wherein saidmaintaining means includes cooperative abutment means of said arm andmounting bracket which are in contacting engagement in the operative andinoperative positions of said arm.

3. The shirring attachment as defined in claim 1 wherein saidmaintaining means includes means for biasingly maintaining said arm ineach of the operative and inoperative positions thereof.

4. The shirring attachment as defined in claim 1 wherein saidmaintaining means includes cooperative abutment means and means forbiasingly maintaining said abutment means in contacting engagement inthe operative and inoperative positions of said arm.

5. The shirring attachment as defined in claim 2 wherein saidcooperative abutment means are defined by a locating abutment surface ofsaid bracket, and a pair of abutment surfaces of said arm definingtherebetween an angle generally equal to the angle set-off between theoperative and inoperative positions of said arm.

6. The shirring attachment as defined in claim 3 wherein said biasingmeans is a spring, and means are provided for adjusting the tension ofsaid spring for selectively varying the holding force of saidmaintaining means.

7. The shirring attachment as defined in claim 3 wherein said pivot pinis journaled in an elongated slot of said bracket, and said baisingmeans applies a force continually urging said pivot pin toward one endof said elongated slot.

8. The shirring attachment as defined in claim 3 wherein saidmaintaining means further includes cooperative abutment means of saidarm and mounting bracket which are in contacting engagement in theoperative and inoperative positions of said arm, and said biasing meansbiasingly maintains said cooperative abutment means in contactingengagement in the operative and inoperative positions of said arm.

9. The shirring attachment as defined in claim 8 wherein said pivot pinis journaled in an elongated slot of said bracket, and said biasingmeans applies a force continually urging said pivot pin toward an end ofsaid elongated slot and toward the abutment means of said bracket.

10. The shirring attachment as defined in claim 9 wherein saidcooperative abutment means are defined by a locating abutment surface ofsaid bracket and a pair of abutment surfaces said arm said arm definingtherebetween an angle generally equal to the angle setoff between theoperative and inoperative positions of said arm, and said elongated slothas a longitudinal axis disposed generally normal to said locatingabutment surface.

11. The shirring attachment as defined in claim 10 wherein said biasingmeans is a spring, and means are provided for adjusting the tension ofsaid spring for selectively varying the force applied to saidcooperative abutment means in both the operative and inoperativepositions of said arm.

12. A shirring attachment for a differential sewing machine comprising amounting bracket, an arm carried by said bracket, first means joumalingsaid arm to said bracket for pivoting movement about a generallyvertical axis between operative and inoperative positions thereof,shirring blade means carried by said arm, second means joumaling saidshirring blade means to said arm for pivoting movement about a generallyhorizontal axis, and means responsive to the pivoting of said armrelative to said bracket about said first joumaling means forautomatically pivoting said shirring blade means about said secondjoumaling means.

13. The shirring attachment as defined in claim 12 wherein saidresponsive means is defined by cooperative cam and cam follower means.

14. The shirring attachment as defined in claim 12 wherein saidresponsive means is defined by cooperative cam and cam follower means,one of said cam and cam follower means being carried by said bracket,and the other of said cam and cam follower means being carried by saidshirring blade means.

15. The shirring attachment as defined in claim 12 including meanscarried by said shirring blade means for overlying a presser foot of asewing machine to impart pivoting movement to said shirring blade meansabout said second journaling means upon upward movement of the presserfoot.

16. The shirring attachment as defined in claim 13 wherein said secondjoumaling means includes a shaft carrying said cam follower means, andsaid cam means is defined by a cam surface in alignment for contact bysaid cam follower means during the pivoting of said arm about said firstjournal means.

17. The shirring attachment as defined in claim 16 including means toselectively vary the throw of said cam follower means to vary the amountof pivoting movement of said shirring blade means.

18. The shirring attachment as defined in claim 17 wherein said secondjoumaling means includes a shaft carrying said cam follower means, andsaid varying means is operative to fixedly secure said cam followermeans at any one of a plurality of different positions about thecircumference of said shaft.

19. The shirring attachment as defined in claim 12 including means forpositively though releasably maintaining said arm in each of theoperative and inoperative positions thereof, said maintaining meansbeing defined in part by said first journaling means, said firstjoumaling means including a shaft journaled in an elongated slot of saidbracket, and biasing means for applying a force continually urging saidshaft toward an end of said elongated slot.

20. The shirring attachment as defined in claim 19 wherein saidmaintaining means further includes cooperative abutment means of saidarm and bracket, and said cooperative abutment means are maintained incontacting engagement in the operative and inoperative positions of saidarms by said biasing means.

responsive to the pivoting of said arm relative to said pivot pin forautomatically rotating said rotary shaft and the shirring blade carriedthereby about said horizontal axis.

1. A shirring attachment for a differential feed sewing machinecomprising a mounting bracket, a pivot pin, means mounting said pivotpin for transverse shifting movement relative to said bracket and to thepivot pin axis, an arm received on said pivot pin for pivotal movementabout the axis thereof between operative and inoperative positions, arotary shaft journaled on said arm, a shirring blade carried by saidrotary shaft, spring means engaging said rotary shaft for biasing saidshaft in a predetermined angular direction, means limiting said angulardistance between said operative and said inoperative positions to 90*,and means for positively though reasonably maintaining said arm in eachof said operative and inoperative positions.
 2. The shirring attachmentas defined in claim 1 wherein said maintaining means includescooperative abutment means of said arm and mounting bracket which are incontacting engagement in the operative and inoperative positions of saidarm.
 3. The shirring attachment as defined in claim 1 wherein saidmaintaining means includes means for biasingly maintaining said arm ineach of the operative and inoperative positions thereof.
 4. The shirringattachment as defined in claim 1 wherein said maintaining means includescooperative abutment means and means for biasingly maintaining saidabutment means in contacting engagement in the operative and inoperativepositions of said arm.
 5. The shirring attachment as defined in claim 2wherein said cooperative abutment means are defined by a locatingabutment surface of said bracket, and a pair of abutment surfaces ofsaid arm defining therebetween an angle generally equal to the angleset-off between the operative and inoperative positions of said arm. 6.The shirring attachment as defined in claim 3 wherein said biasing meansis a spring, and means are provided for adjusting the tension of saidspring for selectively varying the holding force of said maintainingmeans.
 7. The shirring attachment as defined in claim 3 wherein saidpivot pin is journaled in an elongated slot of said bracket, and saidbaising means applies a force continually urging said pivot pin towardone end of said elongated slot.
 8. The shirring attachment as defined inclaim 3 wherein said maintaining means further includes cooperativeabutment means of said arm and mounting bracket which are in contactingengagement in the operative and inoperative positions of said arm, andsaid biasing means biasingly maintains said cooperative abutment meansin contacting engagement in the operative and inoperative positions ofsaid arm.
 9. The shirring attachment as defined in claim 8 wherein saidpivot pin is journaled in an elongated slot of said bracket, and saidbiasing means applies a force continually urging said pivot pin towardan end of said elongated slot and toward the abutment means of saidbracket.
 10. The shirring attachment as defined in claim 9 wherein saidcooperative abutment means are defined by a locating abutment surface ofsaid bracket and a pair of abutment surfaces of said arm definingtherebetween an angle generally equal to the angle setoff between theoperative and inoperative positions of said arm, and said elongated slothas a longitudinal axis disposed generally normal to said locatingabutment surface.
 11. The shirring attachment as defined in claim 10wherein said biasing means is a spring, and means are provided foradjusting the tension of said spring for selectively varying the forceapplied to said cooperative abutment means in both the operative andinoperative positions of said arm.
 12. A shirring attachment for adifferential sewing machine comprising a mounting bracket, an armcarried by said bracket, first means journaling said arm to said bracketfor pivoting movement about a generally vertical axis between operativeand inoperative positions thereof, shirring blade means carrIed by saidarm, second means journaling said shirring blade means to said arm forpivoting movement about a generally horizontal axis, and meansresponsive to the pivoting of said arm relative to said bracket aboutsaid first journaling means for automatically pivoting said shirringblade means about said second journaling means.
 13. The shirringattachment as defined in claim 12 wherein said responsive means isdefined by cooperative cam and cam follower means.
 14. The shirringattachment as defined in claim 12 wherein said responsive means isdefined by cooperative cam and cam follower means, one of said cam andcam follower means being carried by said bracket, and the other of saidcam and cam follower means being carried by said shirring blade means.15. The shirring attachment as defined in claim 12 including meanscarried by said shirring blade means for overlying a presser foot of asewing machine to impart pivoting movement to said shirring blade meansabout said second journaling means upon upward movement of the presserfoot.
 16. The shirring attachment as defined in claim 13 wherein saidsecond journaling means includes a shaft carrying said cam followermeans, and said cam means is defined by a cam surface in alignment forcontact by said cam follower means during the pivoting of said arm aboutsaid first journal means.
 17. The shirring attachment as defined inclaim 16 including means to selectively vary the throw of said camfollower means to vary the amount of pivoting movement of said shirringblade means.
 18. The shirring attachment as defined in claim 17 whereinsaid second journaling means includes a shaft carrying said cam followermeans, and said varying means is operative to fixedly secure said camfollower means at any one of a plurality of different positions aboutthe circumference of said shaft.
 19. The shirring attachment as definedin claim 12 including means for positively though releasably maintainingsaid arm in each of the operative and inoperative positions thereof,said maintaining means being defined in part by said first journalingmeans, said first journaling means including a shaft journaled in anelongated slot of said bracket, and biasing means for applying a forcecontinually urging said shaft toward an end of said elongated slot. 20.The shirring attachment as defined in claim 19 wherein said maintainingmeans further includes cooperative abutment means of said arm andbracket, and said cooperative abutment means are maintained incontacting engagement in the operative and inoperative positions of saidarms by said biasing means.
 21. The shirring attachment as defined inclaim 1 wherein the pivotal movement of said arm relative to said pivotpin is about a generally vertical axis and the rotary motion of saidshirring blade is about a generally horizontal axis, and meansresponsive to the pivoting of said arm relative to said pivot pin forautomatically rotating said rotary shaft and the shirring blade carriedthereby about said horizontal axis.